Fair Values - Fair Value of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financial assets:
Cash and money market instruments	$ 237,699	$ 147,030
Investment securities	1,445,405us-gaap_InvestmentOwnedAtFairValue	1,363,668us-gaap_InvestmentOwnedAtFairValue
Mortgage loans held for sale	5,264	1,666
Impaired loans carried at fair value	16,963prk_ImpairedLoanFairValue	33,819prk_ImpairedLoanFairValue
Mortgage IRLCs	70us-gaap_DerivativeAssets	61us-gaap_DerivativeAssets
Other loans	4,757,461us-gaap_OtherAssetsFairValueDisclosure	4,531,680us-gaap_OtherAssetsFairValueDisclosure
Loans receivable, net	4,779,758	4,567,226
Financial liabilities:
Non-interest bearing checking accounts	1,269,296	1,193,553
Interest bearing transaction accounts	1,122,079	1,145,525
Savings accounts	1,325,445	1,124,994
Time Deposits, Fair Value	1,422,885prk_TimeDepositsFairValue	1,331,129prk_TimeDepositsFairValue
Other	1,269	1,263
Total deposits	5,140,974us-gaap_DepositsFairValueDisclosure	4,796,464us-gaap_DepositsFairValueDisclosure
Short-term borrowings	276,980prk_ShortTermBorrowingsFairValue	242,029prk_ShortTermBorrowingsFairValue
Long-term debt	827,500us-gaap_LongTermDebtFairValue	860,963us-gaap_LongTermDebtFairValue
Subordinated debentures/notes	42,995	83,140
Fair value swap
Derivative financial instruments:
Swaps, fair value	226	135
Carrying value
Financial assets:
Cash and money market instruments	237,699	147,030
Investment securities	1,442,477	1,358,327
Mortgage loans held for sale	5,264	1,666
Impaired loans carried at fair value	16,963	33,819
Mortgage IRLCs	70	61
Other loans	4,753,033	4,525,491
Loans receivable, net	4,775,330	4,561,037
Financial liabilities:
Non-interest bearing checking accounts	1,269,296	1,193,553
Interest bearing transaction accounts	1,122,079	1,145,525
Savings accounts	1,325,445	1,124,994
Time Deposits, Fair Value	1,409,911	1,324,659
Other	1,269	1,263
Total deposits	5,128,000	4,789,994
Short-term borrowings	276,980	242,029
Long-term debt	786,602	810,541
Subordinated debentures/notes	45,000	80,250
Carrying value \| Fair value swap
Derivative financial instruments:
Swaps, fair value	226	135
Level 1
Financial assets:
Cash and money market instruments	237,699	147,030
Investment securities	1,922	1,900
Impaired loans carried at fair value		0
Mortgage IRLCs	0	0
Loans receivable, net	0	0
Financial liabilities:
Non-interest bearing checking accounts	1,269,296	1,193,553
Interest bearing transaction accounts	1,122,079	1,145,525
Savings accounts	1,325,445	1,124,994
Other	1,269	1,263
Total deposits	3,718,089	3,465,335
Level 2
Financial assets:
Investment securities	1,442,708	1,361,009
Mortgage loans held for sale	5,264	1,666
Impaired loans carried at fair value		0
Mortgage IRLCs	70	61
Loans receivable, net	5,334	1,727
Financial liabilities:
Time Deposits, Fair Value	1,422,885	1,331,129
Total deposits	1,422,885	1,331,129
Short-term borrowings	276,980	242,029
Long-term debt	827,500	860,963
Subordinated debentures/notes	42,995	83,140
Level 3
Financial assets:
Investment securities	775	759
Impaired loans carried at fair value	16,963	33,819
Mortgage IRLCs	0	0
Other loans	4,757,461	4,531,680
Loans receivable, net	4,774,424	4,565,499
Financial liabilities:
Total deposits	0	0
Level 3 \| Fair value swap
Derivative financial instruments:
Swaps, fair value	226	135
Available-for-sale Securities [Member]
Financial assets:
Accrued interest receivable	4,048	4,840
Available-for-sale Securities [Member] \| Carrying value
Financial assets:
Accrued interest receivable	4,048	4,840
Available-for-sale Securities [Member] \| Level 2
Financial assets:
Accrued interest receivable	4,048	4,840
Loans
Financial assets:
Accrued interest receivable	13,629	13,495
Loans \| Carrying value
Financial assets:
Accrued interest receivable	13,629	13,495
Loans \| Level 3
Financial assets:
Accrued interest receivable	13,629	13,495
Deposits
Financial liabilities:
Accrued interest payable	1,125	1,366
Deposits \| Carrying value
Financial liabilities:
Accrued interest payable	1,125	1,366
Deposits \| Level 1
Financial liabilities:
Accrued interest payable	14	16
Deposits \| Level 2
Financial liabilities:
Accrued interest payable	1,111	1,350
Borrowings
Financial liabilities:
Accrued interest payable	1,426	1,535
Borrowings \| Carrying value
Financial liabilities:
Accrued interest payable	1,426	1,535
Borrowings \| Level 1
Financial liabilities:
Accrued interest payable	3	4
Borrowings \| Level 2
Financial liabilities:
Accrued interest payable	$ 1,423	$ 1,531

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Short Term Borrowings Fair Value

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Fair value portion of accrued expenses.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Value of the investment at close of period. For schedules of investments that are categorized, the value would be aggregated by category. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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Fair value portion of mortgage loans held-for-sale.

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Fair value portion of other assets.

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